Oxysoft just sent me his complete source code and I tried to figure out how much was actually copied and how much is actually his work.
As it turned out, I was a little bit to harsh on my opinion on oxysoft and I really thought, he just copy & pasted most of the code. PokeSharp is actually based on the Pokemon Dawn Engine and most of its code, even though nearly everything got renamed and refactored, but the huge difference is, that he actually thought about the code and how it works. He read into over 500 classes and figured out how to change and extend the code and even seperated some parts of the engine.
I think "Inspiration from Pokemon Dawn" is credit enough, as he really just uses some parts of the engine and thought about the code in a really deep way not just pasting everything.